WateringTimesWatering plan, $19
Brahea armata, WUCOLS IV

How often to water blue hesper palm in California

In July in the Central Valley, established blue hesper palm in loam needs a deep watering about every 20 days: about 55 gallons each time under a 10 foot canopy, about 19 gallons a week. Blue hesper palm, also called Mexican blue palm, is a slow-growing fan palm from Baja California with stiff, silvery blue-gray leaves 4 to 6 feet wide. Their stalks carry sharp teeth. Long, arching sprays of creamy flowers spill from the crown, followed by round brown fruits, and both leaf and fruit drop can be messy. It is hardy to about 10 degrees F.

TreePalm or cycadRated for 6 of 6 zones

How often to water blue hesper palm, month by month

Your city
Canopy width
10 ft
Your soil

Type your city above and the days between waterings and the gallons appear here, worked out from your city's climate table. Or read the figures by climate zone further down.

Every month, on your water days. The personal plan prints this for blue hesper palm and the rest of your yard, on the days your water supplier allows.Get the plan for $19

How this is worked out: established roots fill the top 1.5 feet of soil, and you water again when that soil has dried halfway. Loam soil holds about 1.5 inches of water per foot. Water the whole area under the branches, and skip a watering after a good soaking rain.

Which soil do you have?

Dig down a few inches, take a handful of moist soil and squeeze it.

  • Sandy: gritty, falls apart when you open your hand, will not form a ball.
  • Loam: forms a soft ball that crumbles when you poke it.
  • Clay: forms a firm, sticky ball and squeezes out into a ribbon between thumb and finger.

Still not sure? Pick loam. Most garden beds sit between sand and clay.

How to measure canopy width

A tree with its canopy width marked across the widest branches and the circle under it shaded blue

Measure across the branches, from the tips of the outer leaves on one side to the tips on the other. A tape works, or pace it out.

Water the whole circle under the branches, shown in blue. The gallons here cover that circle.

A wider canopy means more gallons each watering, not more waterings. While the tree is young, measure again each spring.

How to tell it needs water

  • Deep soil dry around a young palm in its first summers means blue hesper palm can take a slow soak
  • Older leaves browning early in desert heat can follow a dry root zone
  • Rot spreading in the crown after summer water on the leaves points to a wet crown
  • A firm, silvery crown shows the palm is content, even in dry soil

How to water it

  • Water deeply at the root zone, never over the crown
  • Keep the crown dry in summer
  • Plant in full sun for the best color and form
  • Give occasional summer water on the coast and more regular water in the deserts
  • Wear gloves when removing old leaves, since the stalks are toothed

Through the seasons

Water a young palm regularly through its first summers. After it settles, coastal plants manage on little water, though an occasional summer soak improves their look, and desert plants need more regular water. Always water at the roots and keep the crown dry in summer. WUCOLS rates blue hesper palm low water on the north-central coast, in the Central Valley, on the south coast and in South Inland. In the high desert and the low desert it carries a moderate water rating.

In pots

Blue hesper palm grows slowly enough to live in a large, heavy container for years, making a bold silver accent. Use a fast-draining mix. Water at the soil when the top few inches are dry, then let it drain. In summer, check every few days, more often in desert heat. Never leave it in a saucer of water. Keep water off the crown. In winter, water only when the mix dries.

1 Your climate zone six WUCOLS zones, each from its own reference city
1.07gal per sq ft in JulyLow water use in the Central Valley zone
A year
6.84 gal per sq ft
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses
0.761.52.33.00.16JAN0.26FEB0.43MAR0.61APR0.83MAY0.99JUN1.07JUL0.95AUG0.72SEP0.47OCT0.22NOV0.14DEC0.761.52.33.00.16JFM0.61AMJ1.07JAS0.47OND
Gallons per square foot per month, Central Valley. Peak 1.07 in Jul, 6.84 a year.

Monthly water need by climate zone

Blue Hesper Palm: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.150.160.310.310.740.78
Feb0.210.260.320.350.930.93
Mar0.350.430.460.521.461.52
Apr0.470.610.560.641.891.95
May0.580.830.640.782.392.45
Jun0.640.990.690.922.852.79
Jul0.641.070.7913.042.85
Aug0.60.950.740.932.792.6
Sep0.50.720.60.742.142.08
Oct0.350.470.460.531.461.49
Nov0.190.220.330.360.930.96
Dec0.120.140.260.270.650.68
Year4.86.846.27.3721.2721.08

How this is worked out: the WUCOLS water rating for each zone times that zone’s climate for the month. A dash means WUCOLS does not rate the plant there. The figures are what the plant uses, before sprinkler losses.

Plants with the same water needs 16

Rated low water in the Central Valley, like blue hesper palm. Plants that drink alike can share one valve and one schedule.

Olive TreesOlea europaea ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyFig TreesFicus carica ssp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyCrape MyrtleLagerstroemia spp., hybrids & cvs.low water, Central Valley1.07 gal/sq ft in JulyAloeAloe spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyPomegranate TreesPunica granatumlow water, Central Valley1.07 gal/sq ft in JulyEucalyptusEucalyptus polyanthemoslow water, Central Valley1.07 gal/sq ft in JulyPine TreesPinus canariensislow water, Central Valley1.07 gal/sq ft in JulyJunipersJuniperus spp. & cvs.low water, Central Valley1.07 gal/sq ft in JulyTexas Red OakQuercus buckleyilow water, Central Valley1.07 gal/sq ft in JulyPortuguese OakQuercus faginealow water, Central Valley1.07 gal/sq ft in JulySoapbark TreeQuillaja saponarialow water, Central Valley1.07 gal/sq ft in JulyNecklace TreeSophora affinislow water, Central Valley1.07 gal/sq ft in JulyBailey AcaciaAcacia baileyanalow water, Central Valley1.07 gal/sq ft in JulySilver WattleAcacia dealbatalow water, Central Valley1.07 gal/sq ft in JulyGreen WattleAcacia decurrenslow water, Central Valley1.07 gal/sq ft in JulySydney Golden WattleAcacia longifolialow water, Central Valley1.07 gal/sq ft in July
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes blue hesper palm, your sprinkler type and the month, and gives the minutes per water day for that supplier's schedule. Or put it in a zone of the personal watering plan and get all twelve months printed.

Questions people ask

How often should I water blue hesper palm in summer?

In July, established blue hesper palm in loam needs a deep watering about every 20 days in the Central Valley, about every 27 days on the south coast and about every 22 days in the South Inland zone. Sandy soil holds less water, so waterings come closer together. Clay stretches them. Check the soil before each watering and skip one after a soaking rain.

How much water does blue hesper palm need per day?

In July in the Central Valley, established blue hesper palm needs about 2.7 gallons a day under a 10 foot canopy and about 11 gallons a day under a 20 foot canopy. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for blue hesper palm change across California?

Yes. WUCOLS rates blue hesper palm separately for each of the six California climate zones: low water in the North-Central Coastal zone, low water in the Central Valley zone, low water in the South Coastal zone, low water in the South Inland zone, moderate water in the High and Intermediate Desert zone, moderate water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Why must I keep the crown dry?

WUCOLS notes the crown must be kept dry in summer. Water in the crown invites rot. Water the soil around the trunk instead.

Is blue hesper palm drought tolerant?

Once established it needs little irrigation near the coast but looks better with occasional summer water. In desert heat it benefits from more regular watering. Young palms need regular water.

How cold hardy is blue hesper palm?

It is hardy down to about 10 degrees F. It also tolerates desert heat. That makes it useful in many California zones.

Is blue hesper palm messy?

Fruit and leaf drop can be messy. Rake up fruit under the crown. Wear gloves for the toothed leaf stalks.

Where does blue hesper palm come from?

It is native to Baja California. It grows slowly on a stout, gray trunk. Its silvery leaves stand out in a garden.

More plant watering guides

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Sources